A wet clutch for a motorcycle normally includes an inner basket and an outer basket, which are situated coaxially on a main transmission shaft. A number of first friction disks are engaged with the outer basket and a number of second friction disks are engaged with the inner basket, the first and second friction disks being situated coaxially in alternating order. A frictional lock can be produced selectively between the inner basket and the outer basket, by pressing the stack of first and second friction disks against each other axially. A torque of a drive engine is normally input into the outer basket by means of spur gearing, and uncoupled to the main transmission shaft via an internal toothing of the inner basket. The entire clutch runs in an oil bath, which normally also surrounds the transmission.
A number of suggestions have been made for the advantageous design of such a wet clutch. In order to be used in a motorcycle, the clutch must be robust and compact; in addition, it should be producible in large quantities at low cost, and if possible usable with different drive engines. For example, the clutch should also support the link-in of a kick-starter, for example by means of a kick-starter gear connected torsionally to the outer basket.
A usual embodiment for the described clutch uses parts made of a die-cast alloy for the inner and outer baskets. The outer gearwheel for coupling the engine torque into the outer basket is formed in a single piece with the kick-starter gear. The axial clamping force on the friction disks is supplied by means of coil springs. This clutch is relatively complicated to produce, has a high mass moment of inertia, and the clamping force of the coil springs varies over a decrease in height of the friction disks which is a function of wear. Thus, there is a long-felt need to provide a wet clutch for a motorcycle, which fulfills the demands described above in an improved manner.